When it comes to comparing different press technologies (pneumatic, hydraulic, servo), one of the common arguments manufacturing engineers like to make is: “it’s a cylinder that goes up and down. Other than force range, as long as it goes up and down, how different can they be?”
While force range may certainly be a limiting factor for some technologies, it is far from the only factor. The truth is, there are many, more crucial factors, that are often being overlooked. Many of which may seriously affect the quality of your assembled products AND the true COST of the system over time.
Among these factors, beyond mere up-front price, are accuracy, repeatability, responsiveness, programmability, data and energy usage:
| SERVO | HYDRAULIC | PNEUMATIC | |
|---|---|---|---|
| Force Range | Capable of Range from significantly less than 1N up to 1MN | Capable typically of range from 50kN to >1MN | Capable of lower force range typically up to = 50kN |
| Accuracy | Accurate to within mere ounces throughout full range of press | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Repeatability | Repeatable positionally to within microns & to within Fractions of a Newton | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Responsiveness | Capable of incorporating real-time in-process feedback and adjusting “on-the-fly” | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Programmability | Fully Programmable for Accurate Force & Position throughout entire Range, as well as for Multiple Part Models on same line | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Data | Complete captured & gauged (by integrated sensors) for every part produced which can be stored for Product & Process Verification as well as Process Improvement | No Data | No Data |
| Energy Efficiency | Only Consumes (significant) Power during Active Cycle | Constantly consumes significant Energy maintaining Hydraulic Pressure and Wastes Significant Energy in the Form of Heat. Also Prone to Leaks and affected by Ambient Conditions | Constantly consumes Energy maintaining Pneumatic Pressure and is very Prone to Leaks |
| Cleanliness & Safety | Safest, Cleanest & Quietest Option: No Messy Oil to Spill and Leak & Capable of Sensing Unsafe Conditions BEFORE Unfortunate Incidents occur | Notoriously Dirty and known for Creating Unsafe Conditions from Leaking/Spilled Hydraulic Fluid. Typically, loud | Known to Aerosolize various Materials (i.e., Lubricating Oil). Typically, loud |
So sure, there are manufacturing technologies that “go up and down” to press parts, but THEY ARE NOT ALL THE SAME.
All Electric Servo-Press Systems, such as those provided by Promess Inc., offer clear advantages, as well as lower cost of ownership over the life of the system.